1. Field of the Invention:
The present invention relates generally to heat exchangers and, more particularly, to heat exchangers which utilize swirl flow fluid passages. Even more specifically, the present invention relates to the use of a swirl flow conduit in which a reverse spiral configuration is used.
2. Description of the Prior Art:
Many different types of apparatus have been developed for the purpose of transferring heat from one fluid to another. Typically, this type of apparatus provides a means for conduction one fluid through a heat exchanger in such a way that it passes in thermal communication with a second fluid which is also conducted through the heat exchanger.
U.S. Pat. No. 4,352,273, which issued on Oct. 5, 1982 to Kinsell et al, describes a fluid conditioning apparatus and system in which a working fluid from an external source which is to be conditioned in heat exchangers and fluid conditioning means is admitted to the passage ways of a heat exchanger and to a bypass around the passage ways of the heat exchanger to provide a fluid from the passage ways in a final condition tempered by the bypass fluid.
U.S. Pat. No. 4,300,627, which issued on Nov. 17, 1981 to Cleveland et al, describes an insulated housing for ceramic heat recuperators in which cross-flow ceramic recuperators are disposed in an assembly in which the ceramic recuperator is held by a metalic housing which is adapted for retrofitting to the metalic fitting of existing furnaces, ovens and preheaters. The assembly is characterized by at least two insulating layers inside the conduit portions leading from the operating hot faces of the ceramic core. This structure increases the operating efficiency of the assembly.
U.S. Pat. No. 4,282,927, which issued on Aug. 11, 1981 to Simmons, describes a multi-pass heat exchange circuit which incorporates a concept for reducing the number of parts in a plate and fin type heat exchanger in which a fluid makes plural passes at least at one level of the heat exchanger. In this device, a single layer of a secondary heat transfer material replaces multiple detail parts of the prior art and is appropriately configured in conjunction with flow divider members to assure continuous fluid flow to and between fluid passes.
U.S. Pat. No. 4,178,991, which issued on Dec. 18, 1979 to Bieri, describes a heat exchanger and a heat exchanger element in which the element is constructed with radially disposed walls so as to sub-divide the element into flow zones with alternating zones carrying first and second heat exchange media. The alternating zones convey the media in opposite directions to carry out the heat exchange operation. The walls may be of flat shape disposed in a radial pattern or may be formed of corrugated plates interspersed between flat walls.
U.S. Pat. No. 4,099,928, which issued on July 11, 1978 to Norback, describes a method of manufacturing a heat exchanger body for recuperative exchangers in which the manufacturing method relates to a heat exchanger body composed of a plurality of facially opposed corrugated rectangular sheets of a deformable material with corrugations in alternate sheets crossing the corrugations in the intervening sheets and forming a series of channels through which two streams of gaseous medium are forced crosswise in heat exchange relationship with one another. The juxtaposed edges of the sheets are displaced so that the edges on the same side of the body are alternately sealed and form openings therebetween for admission of the gaseous media into the channels.
U.S. Pat. No. 3,925,021, which issued on Dec. 9, 1975 to Yoshino et al, describes an apparatus comprising a plurality of chemically treated absorption plates for injurious gases contained in the air. It describes a device for removing acidic and injurious gases such as a sulfur dioxide gas and a hydrogen sulfide gas or acid mist from the air comprising a plurality of absorption plates, spacing means positioned for maintaining the absorption plates apart to form a plurality of layers so as to pass air through the space between the layers.
U.S. Pat. No. 3,705,618, which issued on Dec. 12, 1972 to Jouet et al, describes a heat exchanger of a generally cylindrical shape which includes a structure having at least two chambers being wound on themselves in self-enclosing spirals, baffles forming passage ways through the chambers to facilitate the flow of heat exchanging media through the chambers in alternate centripetal and centrifugal relationship.
U.S. Pat. No. 3,610,331, which issued on Oct. 5, 1971 to Schreiber, describes a heat exchanger which is composed of a plurality of discs arranged adjacent to each other. Each of the discs comprises two complimentary plates which are connected to each other by cementing, welding or the like and when so connected form with each other spiral shaped flow passage means.
U.S. Pat. No. 3,323,587, which issued on June 6, 1967 to Lowell, describes a rolled plates cooler wherein the basic component of the heat exchanger is a plate of an elongated configuration having high heat transfer characteristics. The plate can be formed of two interconnected plate elements or formed from a single plate element and is definedd by end edges and longitudinal edges. Four header tubes are associated with the plate and the transversly disposed thereto.
U.S. Pat. No. 4,460,388, which issued on July 17, 1984 et al, describes a heat exchanger that comprisesan elongated plate folded in corrugated fashion and defining a stack of a number of laminated air passages defined by spacer parallel plane heat transfer faces or plates connected alternately along opposite side edges by narrow partition plates. In alternate air passages, spacer plates are disposed having such a wavy or corrugated configuration as to conduct a first current of air flowing into such alternate passages from one open end thereof to flow out of an open side portion thereof opposite the corresponding partition plate.
U.S. Pat. No. 4,473,111, which issued on Sept. 25, 1984 to Steeb, discloses a heat exchanger which incorporates an improved sandwich type core construction. Passages of one set are interleved with those of another set, using spaced parallel heat transfer plates. Elongated parallel spacers extending in one direction established flow passages of one system while elongated parallel spacers extending in a different direction establish flow passage of a second system between paired plates of the first system.
U.S. Pat. No. 3,058,722, which issued to Rich on Oct. 16, 1962, discloses a heat exchanger which is particularly useful as a condenser or evaporator unit in a mechanical refrigeration system. It comprises a substantially conical coil made of tubing-strip material which may be formed either of parallel strips linearly expanded along restricted zones to form the tubes or, alternatively, by extrusion of any other suitable process. The device has a central vertical tube which is connected by tubing to the inner ends of two tubes which are each arranged in an outward spiral which begins at the vertical header tube in the center of the dual spiral and ends at a header conduit that is disposed radially outward from the centrally disposed vertical header tube. While the structure incorporates a tubular pattern that resembles a reverse spiral structure, it does not direct a fluid flow in a reverse spiral path and, furthermore, the fluid conduits described in the Rich patent are not confined within a generally planar region.
U.S. Pat. No. 4,445,569, which issued on May 1, 1984 to Saho et al, describes a scroll type laminated heat exchanger. The device relates to a laminated heat exchanger having a laminated construction consisting of a plurality of perforated heat tranfer plates and spacer arranged alternatingly, the spacers defining a plurality of fluid passages between respective adjacent heat transfer plate so that heat is exchanged between different fluids flowing in different fluid passages through the heat transfer across the heat transfer plates. The invention is concerned with a heat exchanger of the type described above wherein a plurality of separate scroll passages are formed by the spacer so that local concentration of each fluid in its passage is avoided for the purpose of improving the heat transfer efficiency. This device incorporates fluid passages which are formed between solid portions of a heat transfer plate in which the solid portions are shaped in a reverse spiral configuration. The reverse spiral configuration of solid material defines two distinct fluid passages which are each generally spiral in shape and which are maintained in fluid isolation from each other.
When spiral tubes are used in a heat exchanger and the spiral tubes are confined in a planar region, one end of the tube is typically disposed in an outer position relative to the spiral and the opposite end of the tube is disposed at a position that is centrally located within the spiral configuration. While this type of arrangement provides a generally acceptable heat transfer device, it presents a problem relating to connections between the spiral tube and external devices. This problem becomes especially acute when multiple spiral configuration are interconnected with each of the individual spiral tubes being located in a planar region and the planar regions of the plurality of tubes are arranged in parallel association with each other. This type of configuration usually requires some means by which all of the inner ends of the individual spiral tubes must be connected in the central region of the spiral tubes. This presents a problem relating to the manufacturing technique and the structural design of this type of heat exchanger. A significant manufaturing benifit can be ortained if both ends of the spiral tubes can be disposed at locations that are outward from each of the spiral configurations. This type of arrangement would provide for easier manufacturing of the heat exchanger and would simplify repair.
U.S. Pat. No. 4,697,427, which issued to Niggemann et al on Oct. 6, 1987, describes a forced flow evaporator for unusual gravity conditions. Low efficiency heat transfer in evaporators which are subjected to unusual gravitational conditions is avoided through the use of a spiral evaporator conduit which receives, at an inlet, a vaporizable coolant which is at least partly in a liquid phase. Flow of this coolant through the conduit demists the coolant by centrifuging the liquid phase against a pressure wall of the conduit. Vapor flow induces counterrotating vortices which circulate the liquid phase coolant around the interior of the conduit to wet all surfaces thereof. One embodiment of the evaporator described in the Niggemann et al patent incorporates a spiral tube which is configured to provide both an inlet and an outlet that are both disposed radially outward from the central portion of the spiral configuration. That alternative embodiment incorporates a reversal of the spiral at a region is inwardly disposed within the planar region of the structure.